1 Cell battery LED flasher circuits


Posted on Feb 13, 2013

The LED flasher circuits below operate on a single 1.5 volt battery. The circuit on the upper right uses the popular LM3909 LED flasher IC and requires only a timing capacitor and LED. The top left circuit, designed by Andre De-Guerin illustrates using a 100uF capacitor to double the battery voltage to obtain 3 volts for the LED. Two sections of a 74HC04 hex inverter are used as a squarewave oscillator that establishes the flash rate while a third section is used as a buffer that charges the capacitor in series with a 470 ohm resistor while the buffer output is at +1.5 volts. When the buffer output switches to ground (zero volts) the charged capacitor is placed in series with the LED and the battery which supplies enough voltage to illuminate the LED.


1 Cell battery LED flasher circuits
Click here to download the full size of the above Circuit.

The LED current is approximately 3 mA, so a high brightness LED is recommended. In the other two circuits, the same voltage doubling principle is used with the addition of a transistor to allow the capacitor to discharge faster and supply a greater current (about 40 mA peak). A larger capacitor (1000uF) in series with a 33 ohm resistor would increase the flash duration to about 50mS. The discrete 3 transistor circuit at the lower right would need a resistor (about 5K) in series with the 1uF capacitor to widen the pulse width.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Loudspeaker Protection 2
Voltage regulator for projection lamp
Ni-cad charger
Color-Bar Generator
DIY intervalometer for Sony NEX
gym agility simple strategy
RF field detector circuit diagram
Ultrasonic parking sonar circuit design project
6V 9V adjustable flow circuit
Line current measurement circuit



Top